It is known to the artisan, that continuously variable transmissions gain in importance, since motor-vehicles equipped with such transmissions have a very good efficiency, low noise level and low fuel consumption.
It has to be distinguished between pushing belt and pulling chains.
A well known pushing belt is for example the CVT-transmission with Van-Doorne pushing belt (Antriebstechnik 26, (1978) Nr. 8, pages 47-52).
Lubricants are of great importance for pulling chains and pushing belts. Lubricants should not only possess good lubricant properties in order to minimize wear at chains, but in addition they must have a specific coefficient of friction. The coefficient of friction must be higher compared to convential lubricants, however not as high as in the case of so-called traction fluids.
In the latter case a coefficient of friction as high as possible is preferred, because the additional property to have good lubrication properties with regard to the chain links is not required, because disks or wheels are in close contact to each other, the percentage of slip of which should be as small as possible. If the speed of rotation of one body is V1 and the speed of rotation of another body is V2, the coefficient of percentage of slip is defined as ##EQU1##
Lubricants for pulling chains are known in the literature. Thus DE-OS 31 27 970 discloses a lubricant, which consists of a hydrogenation oil, which contains hydrocarbons with 19-30 carbon atoms as well as three six-membered carbocyclic rings.
In DE-OS 33 21 773 a lubricant is described, which contains carbon atom bridges connected by decalin/rings.
In DE-OS 33 37 503 a lubricant is disclosed by the same applicant, which also contains hydrogenated condensed aromatic rings.
Phosphetane derivates as additives in conventional lubricants are disclosed in DE-OS 27 15 529.